Personal Interest Project: Tractors and Compaction in Orchards
Theresa Werme
6/25/2012
I would like to share my opinion on orchard management and soil compaction. The described methods are not the only way to manage an orchard, but are what I have used with a few new ideas added in. A commercial orchard operation requires year-round management and care in order to produce apples. If you have an orchard, and one tree has a problem, that problem can spread easily. Many commercial apple-growers spray something and use need heavy machinery to do so. In a sample spray schedule for an organic orchard, the UMASS Extension suggests spraying nutrients, insecticides and fungicides adding up to about 35 trips down each row. In a compact tractor, doing that every year, just for spraying, could potentially create heavy compaction. There are multiple types of sprayers. An orchardist can walk around with or drive around on a tractor using a handgun sprayer, or, more likely, choose from a variety of tractor attachments.
In addition to spraying, tractors are used in orchards to mow. According to the 2011 New England Fruit Tree Management Guide, “mowing is the most important orchard floor management tool.” The orchard floor affects the health of the trees in many ways. If the floor is wild and filled with hardy weeds, they could compete with young trees or provide rodents with the perfect habitat. If this is the case, you will need to mow more often, so one way to reduce compaction is to plant a slow-growing grass such as a fescue. That way, says the Guide, you will mow much less often. Also, if using conventional methods to maintain the orchard floor, one should try to be reasonable. For example, if a conventional orchardist maintains a narrow strip (maintained with herbicide) underneath the trees, natural predators of mites are more likely to move from the grass to the trees. If the strip is too wide, however, there will be more problems and fewer benefits. Bare soil (the “clean cultivation” method) can increase risk of soil erosion. If this method is used, it is important to have a fall cover crop. If not, the roots will be susceptible to frost damage. “In addition to these potential risks, calcium availability to trees may be reduced and soil compaction problems may develop” with repeated cultivation (2011 New England Tree Fruit Management Guide). In my opinion, the best bet is to plant a slow-growing grass when starting a new orchard, and then maintain that with a mower.
There are two types of mowers useful for orchards: the rotary mower and the flail mower. The rotary mower requires less horsepower and can reach further under the trees. The flail mower requires more horsepower, but is able to chop up fallen wood and prunings and return them to the soil, which is good orchard practice, as long as they are not diseased (Orchard Equipment).
How does compaction affect the trees? Compaction alters how porous the soil is. The sizes of the pores in soil control ease of absorption of air and water, soil fertility, and the root growth of the plants (Vogeler, Iris; Cichota, Rogerio; Sivakumaran, Siva; Deurer, Markus; McIvor, Ian ). Compaction has been said to increase risk of root diseases and restricts feeder roots and also affects fruit yield negatively (Biological Approaches to Sustainable Soil Systems).
What can be done to lessen the effects of compaction? In orchards, you could till the soil and plant a cover crop. One such tiller is “The Aerway® AWV3 models … designed to eliminate soil compaction, reduce runoff and improve moisture retention without destroying the soil structure in orchards and vineyards (Taskpower). Another method is deep plowing. In an experiment with a “wing-delve plow to a depth of 80 cm at a distance of 1 m from the tree stems on one side of tree rows, followed with deep plowing on the other side 16 months later,” “deep-plowed soil showed strong root regrowth at 20-80 cm soil depth compared to fewer roots in the unplowed soil” 18 months later and the feeder roots, where pruned, showed “prolific regrowth.” Furthermore, fruit size and yield were said to improve significantly (Biological Approaches to Sustainable Soil Systems). Another technique is to compost and mulch under apple trees. It becomes a personal choice of what to do because these methods involve the use of heavy machinery, and some present the risk of erosion. It all comes down to what you think will be most effective.
Lorraine P. Berkett, Renae E. Moran , M. Elena Garcia, Heather M. Darby, Robert L. Parsons, Terence L. Bradshaw, Sarah L. Kingsley-Richards, and Morgan C. Griffith, . “Orchard Equipment.” Practical Guide for Organic Apple Production. OrganicA, n.d. Web. 10 Aug 2012. <http://www.uvm.edu/~organica/PracticalGuide/OrchardEquipment.html>.
Taskpower, . “Aerators: Orchards and Vineyards.” Taskpower: New Zealand Limited. Zeald, 2010. Web. 10 Aug 2012. <http://www.taskpower.co.nz/AERATORS/Orchards and Vineyards.html>.
Vogeler, Iris; Cichota, Rogerio; Sivakumaran, Siva; Deurer, Markus; McIvor, Ian, . “Soil assessment of apple orchards under conventional and organic management.” Australian Journal of Soil Research. (Dec. 1, 2006): n. page. Web. 10 Aug. 2012. <http://www.thefreelibrary.com/Soil assessment of apple orchards under conventional and organic…-a0157032846>.
Norman Uphoff, Andrew S. Ball, Erick Fernandes, Hans Herren, Olivier Husson, Mark Laing, Cheryl Palm, Jules Pretty, Pedro Sanchez, Nteranya Sanginga, Janice Thies, First. Biological Approaches to Sustainable Soil Systems. March 3, 2006. eBook. <http://books.google.com/books?id=XO3pio5Opy8C&pg=PA552&lpg=PA552&dq=soil+compaction+in+orchard&source=bl&ots=Rklgxe1rXT&sig=UT8jH7XwuinIrvXM7T929QISAPU&hl=en&sa=X&ei=WHQkULuGOI6f6QGIqoGQBQ&ved=0CD4Q6AEwAQ#v=onepage&q=soil%20compaction%20in%20orchard&f=false>
Cooley, Daniel R., Lorraine M. Los, George Hamilton, et al. Cornell, UCONN, UMASS, UNH, UVM, University of Maine Extensions. “Groundcover Management.” 2011 New England Tree Fruit Management Guide. 2011. Print.
Theresa Werme 